1. Field of the Invention
This invention relates to hard space suit joints, especially for the shoulder and hip. It may also be used on diving suits, manipulator arms, user-occupied arms for penetrating boxes such as autoclaves, high vacuum boxes for integrated circuit work and the like, which require protection from hostile environments. The joint has an outer covering of a relatively rigid material in three articulated sections, each of which is a section of a sphere.
2. Description of the Prior Art
U.S. Pat. No. 3,405,406 discloses a hard space suit having a three-bearing, two-section shoulder joint and a bellows hip joint. The shoulder joint has a centrally-situated dead zone into which the centerline of the bicep bearing cannot intrude. Accordingly, the wearer of the joints prohibited from placing his arm in a zone that coincides with an imaginary axis extending horizontally from the wearer's arm socket. The present invention permits the wearer to point his arm anywhere within a solid cone whose apex is located at the arm socket. The angle of the cone may approach 180 degrees.
U.S. Pat. No. 4,091,464 reveals a space suit which has some hard portions and some soft portions. Each leg of the suit is joined to the torso by a single ball bearing. This limits the freedom of leg motion of the wearer. The shoulder joint utilizes link-connected rings which are covered with a rolling-convolute variety diaphragm. The present invention has a plurality of independently rotatable rigid truncated spherical sections. The sections are inconnected with ball bearings and their axes of rotation are arranged in such a manner as to provide a minimal envelope for a given limb diameter and limb clearance.
U.S. Pat. No. 3,712,481 discloses a snakelike actuator for use on submarines and so forth that is motor actuated, whereas the present invention requires no motors and is actuated by movement of the limbs of the wearer. The snakelike actuator arm comprises a continuous bellows outer layer which provides a hermetic seal plus two inner layers, each of which comprises alternate cylindrical wedges and bellows. In a second embodiment the actuator arm comprises three bellows layers plus a layer of rotatable wedges. In each instance the arm is moved by means of torque motors coupled to the layers.
The paper "High-Pressure Protective Systems Technology" by Hubert C. Vykukal and Bruce W. Webbon, ASME Publication 79-ENAs-15, 1979, refers to a data supplement (last sentence before Conclusions) which has conceptual drawings of a three-section, four-bearing shoulder joint. Each section is able to rotate independently of the section adjacent thereto. The angle included between the ends of the middle section is double the included angle associated with each end section. Inasmuch as the section angles are unequal, the joint is prone to lockup, the condition where the joint will not follow a desired planar flexure of the wearer and where the centerline of the distal end bearing randomly deviates from a plane and the sections impose shear forces on the wearer that could be severe enough to be injurious. The present invention utilizes sections with equal angles and obviates lockup. The bearing centerlines in the present invention are disposed in such a manner that a minimum joint envelope results. Stated another way, for a given limb diameter and limb tunnel clearance, the joint of the present invention is optimally small. The Position A part of FIG. 11 shows that the conceptual joint does not have a minimum envelope (the limb clearance space at the first bearing is much larger than the clearance space for the smallest diameter bearing). From cost and weight standpoints, it is of course desirable to have a joint that occupies minimum volume.